Preloading of bogies for motor cranes and the like



4: J,(9.4 44034 W la June 24, 1952 zElLMAN 'ETA 2,601,486

PRELOADING OF BOGIES FOR MOTOR CRANES AND THE LIKE Filed June 16, 1948 avev" 38767" IN V EN TORS 2437 52767 av-rgzmsys MAPT/N L SHEET P YH. ZEILMAN 6ND.

Patented June 24, 1952 PRELOADING F BOGIES FOR MOTOR CRANES AND THE LIKE Roy H. Zeilman and Martin L. Sheetz, Elyria, Ohio, assignors to The Thew Shovel Company, Lorain, Ohio, a corporation of Ohio Application June 16, 1948, Serial No. 33,308

8 Claims. (01. 280-104.5)

The present improvements, relating generally as indicated to preloading of bogies for motor cranes and the like, have more particular re gard to novel preloading means designed for enabling the handling of greater loads by the crane without requiring added counterweight, shortening of the crane boom or shifting of the bogie and crane relative to one another on the vehicle chassis.

Ordinarily motor cranes are mounted on chassis commonly referred to as "six wheelers which comprise a frame with a front axle and two rear axles suspended therefrom, the latter axles being part of a bogie of which either'or both are provided with differential gearing driven through a rotary propeller shaft extending rearwardly from a gear box associated with the vehicle engine. However, insofar as the principal features of this invention are concerned, specific reference to such motor cranes and to particular bogie constructions is to be regarded as merely exemplary, it being understood that the manner and mechanism for preloading bogies herein disclosed may be equally well suited to the preloading of bogies of semi-trailers of the type adapted to be coupled with a tractor by means of the usual fifth wheel to thus constitute a so-called tractor-semitrailer.

It is, as indicated above, one of the principal objects of this invention to provide a novel manner and means for preloading bogies whereby to increase the load carrying capacity of a crane or the like mounted on the frame of the chassis or semi-trailer, such increased capacity being obtained without impeding bogie action, without requiring adding or shifting of counterweights on the frame, and without varying the crane operating radius.

Other objects and advantages will become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims,the following description and the annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawing:

Fig. 1 is a perspective view of the rear portion of a truck chassis illustrating a preferred embodiment of the present invention in association with the bogie suspended from said chassis;

Fig. 2 is a schematic side elevation view of the bogie preloading mechanism;

Fig. 3 is a schematic representation of a typical motor crane without the present improvements thereon;

Fig. 4 is a view similar to Fig. 3 in all respects except that the present improvements are associated therewith; and.

Fig. 5 is a rear elevation view of a portion of a bogie preloading mechanism of a slightly modified form.

Referring now to the drawing, and first more especially to Fig. 1 thereof, there is illustrated therein the rear portion of a six wheeler comprising a frame 1 including longitudinally extending side rails 2 and 3 and cross members 8 and 5 projecting laterally beyond said side rails to provide outrigging adapted to be blocked for lifting loads from the sides of the frame.

Suspended from said frame I is a bogie 5 of any desired construction, herein shown as comprising a pair of rockers or Walking beams 7 pivoted about trunnions 8 on opposite sides of said frame, said trunnions being preferably disposed, as best illustrated in Fig. 2, in line or slightly below the centers of the front and rear axles 9 and Ill respectively fastened to the opposite ends of said rockers whereby tov eliminate or counteract the pole vaulting effect otherwise encountered when the brakes of the two pairs of wheels II and I2 on said axles are applied. In the particular bogie 6 illustrated herein the rear axle Ill thereof is provided with differential gearing driven by a rotary propeller shaft I4 extending forwardly of the frame to a gear box (not shown) which isdisposed rearwardly of the vehicle engme.

The bogie 6 just described may be either of the single suspension type wherein the parts denoted by the numeral 1 are leaf springs pivotally connected to trunnions 8 fixed on the frame or alternatively of the type in which the parts 1 are rigid beams pivotally connected to trunnions 8, the load being carried by springs interposed between said frame and trunnions. Other typesof bogies which may be employed with the preloading mechanism to be presently described include the reach member construction inrwhich is provided a rigid reach member from axle to axle to which leaf springs are clipped at the middle, said springs being shackled at their ends to the frame; the separate spring suspension type in which the inner ends of separate springs for each axle are joined by an equalizer bar pivoted to the frame; the radius rod type in which radius rods pivoted close to the trunnion serve to position the axles and to transmit brake torque, and the other well known types employing equalizer bars, bell cranks, parallelogram, and other torque rod systems.

The front end of the truck is of a conventional form comprisinga cab 15 (see Figs. 3-.and 4) and propelled or through the truck-=engine, usually the latter, is a crane generally designated by the numeral H in Figs. 3 and 4, said cranedncluding an operators compartment l8 therein, said crane I? and cab I5 being preferably so formedthat the crane may be positioned with its pivoted boom I19extending..f0rwerd1mand1alongside;s cab l5 as when the trrmkd ztravelineifromsone job .to another. 1Within;saidicrane oompartmen 10 :is the usiia1 two-drum "arrangement when hoisting is to be done with a hook or armagnet, on drumflbein employedffon:raisingiand lowering the. boom 19: andxthegother.drum-beingemployed for raising the load,:attac;he,d-:toithehook or magnet. Obviouslyadditional:drumsmaybe required if :a grab-bucketor thelike ;is1employed.

Referring now to the bogie preloading mechetnism, the same'comprisesiront, and rear pairs of longitudinallyxspaced obracketsj'r :and 21- son said side :rails :Zand 5.3,:said :pairs of ibrackets being, disposed ;on oppositesides or the trunnions 8 and fixed on; the respective siderails. by bolting, welding, or other suitable ;:means. Journalled in. the-pairs ,ofizbracketsiwrand ;2 :are:.the opposite. lendsoof tOISiOIlzzSPIiIlg ;bars 23 and :24.

Adjacent .eachlend. .ofsaidrbarszfl and, 24wand non-rotatable lthereonsas through ;a .splined or axially serrated connection aare-inwardlyzdirected 7 pairs of front levers: 2 sandl rear levers :lfir-having pairs of front-and rearidrag; links :fland 281'1'6- spectively connected :to 1 their inner ends, said front drag links"?! in turn'ihaving .their;\ver ends connected to the opposite ends .of an equalizer bar 29 -and said rearrrdrag links 528 having their lower ends connecteditotheyopposite-aends of an equalizer bar 7:30. {Said equalizer: bars:-.29 andl arerespectively pivoted attheir centers on thefrontand rear axlesriaand ll-of said bogie 6. The connections .of the =drag:'linksii2l:arid 28 with the equalizer. bars: 29 land :-:30;;an'd levers 12.5 and '26 :are preferably :of the nom-plementaryzball and socket type widely usediin :therautomoti-ve industry.

Said dragzlinks-rzl andrzfla'arerenderedgadiustable in lengtheas by providing :end-amembersjl and 3.2 respectively formed :with qleithaind and righthand threadslin which areythreaded' theropposite ends :of 21.111011? .33, rotation :of said TbQlt thereby providing .a turnbuckle adjustment of said drag. links.

Predetermined adjustment 10 :hh fflb9Y1 scribed iboeie prel a me hanism may be .ae f ected' as'follows (I) The if-ront :and rear vlevers 25 ;and 26 are mounted 1 on :the associated torsion 1 spring bars 23 .andj2'4so asztozbeflis posed atarp gedetermined angle correspondingto: the :desired de ree of preloading.

.(2) Thefronkdraa-links .121 ar th n a just d so that :when the =front"axle:,9 f'-.the:-bogie-;is 1in its normal position, intermediat "its. uppermost.

fit)

'll. zseen that the front axle 9 and wheels ll thereand lowermost positions, as shown in Figs. 1 and 2, said front equalizer bar 29 and said front levers 25 will be in a horizontal position, the rear levers 26 then being inclined downwardly at an angle corresponding with the desired amount of preloading as aforesaid.

(3) The-rear drag links212'8" are" then adjusted to twist the bars 23 and until the-rear levers 26 are parallel with the front levers 25, said rear equalizer bar 30 then being parallel with the front ,.equalizer.bar. 2 9.

"withgsuch above adjustments made, it is now evident that the rear drag links 28 will be under ;compression-rand that the front drag links 2? will'be under-tension respectively exerting downwardforee-"on-therear axle l0 and wheels 12 and upwardforceon the front axle 9 and wheels With respect to the bogie action, it can be on in moving upwardly .will permit an untwistingvotthe bars". 23 :2,4=.ther.epy. reducing the sererityof shocks whenrthezfront wheels. encounter arqadbump. @Qnt-the other hand;;movement of-rsaid front raxleeaiand-wheels H downwardly Millefiect -a further twisting of said bars; 23 :and 24 to thusgincreasei,thetension onzthe front drag links whereby' -the-contact-pressure between the front -w.he,els'.and' the pavementawill be still further reduced. It is to be observed thatthe bogie action as .to the raising :and lowering of .the

wheelsdl ,relative-to -one another and similarly of the .wheelsnllmelative zto: one- 'anothrei is not in any way interfered with. --As is apparent, the equalizer tbarsllfiwand 30=are operative to dis tribute excessive loadsfrom ..one-.wh eel to the others; V

Following, .is .a.,list of the formulae which may bemused for ..'determining the proper size of the bars '23 arid 2Z4, together with .a typical. sample calculation 1f0r ,predeterminately preloading a bogie. V t V 11 x2sLR (2) ZSLR (3) 5103211 5 49i? 1 "QL'R (:5) r0R w L he sprin xbars 23 :andr24:must.each:.be 2,000

lbs-L25" ;or .1800 abs. periinchwhichiin turnaroquires total deflection :of ,"000/800 131' 1125' f..

X56X68 9000 11,000,000 X 11.25

d=41/2.775=,l.291 Then, using formula (4) with deflections of 8.75, 6.25, and 11.25, the following stresses are obtained, via:

11,000,000 X 1.291 X 8.75 2 X 68X 7.5

.l22,000#/Sq. In.

11,000,o00 1 .291 6.25 2 X es 7.5

87,000#/Sq. In.

157,o00#/sq. In. Thus the spring bars 23 and 24 may be fabricated from chrome vanadium steel for example properly heat treated and shot peened to raise the elastic limit to 1'75,000-265,000 lbs. per sq. in. which is adequate for the above noted stress range of 87,000 per sq. in. to 157,000 lbs. per sq in. With an axle distance of 52 and a distance of 120 from the center of rotation of the crane to the hook thereof, or 93" from the trunnions 8 to the hook, the maximum additional load regardless of where the connections are made on the axles which it is possible to lift at any distance is the amount caused by the couple in the frame, which in this case amounts to 52'' X the load in the spring divided by any distance selected from the center line of the couple to the center line of the load. Therefore, the increase in static lift will be 52 x 14,000/93=7840 lbs., and the increase in moving lift will be 52 X 10,000/93=5,370 lbs.

As a further example, a comparison of Figs. 3 and 4 will reveal that the installation of the present preloading mechanism without any other changes effects an increase of 8,300 lbs. additional capacity, viz. 41,800 minus 33,500. In 3 the tipping line of the chassis is at the trunnions of the bogie whereas the effect of the preloading mechanism thereon, as shown in Fig. 4, is to shift such tipping line rearwardly in direct proportion to the ground reactions 24,767 52,767 of the bogie wheels or 77,534 lbs. whereupon 77,534/24,'767:.32 or 32%, and 77,534/52,767==.68 or 68%., Then 68% of 4,333 feet, the axle distance of the bogie, or 2,946 feet is the tipping line distance from the front bogie axle 9. Thus, the new tipping line moves rearward .780, viz. the difference of 2.946 and 2.166. The new moment of stability is equal to 44,034 lbs. x 6.653 or about 292,000 foot lbs., and the radius to the load is then equal to 6.970 whereupon the lifting capacity with the boom head of Fig. 4 is 292,000 foot lbs/6.970 or 41,800 lbs., thereby providing an increased capacity of 8,300 lbs. over the 33,500 lbs. as shown in Fig. 3. The diagrams in Figs. 3 and 4 represent a substantially balanced condition except for a safety factor as indicated by the figure 2'770# at the front end of the chassis.

With reference to Fig. 5, the same illustrates a modification in which a hydraulic cylinder 34 is Preload Stress:

Maximum Stress:

substituted for the rear drag link 28, said cylinder being actuatable at will and with a desired variable pressure in line 35 (connected to said cylinder and leading from a pump or the like) to effect predetermined preloading. With such substitution it is more convenient to preload the bogie during use of the crane and to relieve the preloading at all other times. In this modification, a cylinder 34 may be associated with each of the rear drag links 28 or optionally with each of the front drag links 21 and simultaneously actuated to equally preload both spring bars 23 and 24.

Although certain difliculties are encountered in the application of fluid cylinders for preloading, it has been found that in some instances it may be feasible to effect the desired rearward shifting of the tipping line of the frame I relative to the trunnions 8 by the interposition of a fluid cylinder between the rockers I or exten sions thereof or on either or both of the axles 9 and I0 and the frame I at a point spaced from said trunnions for the purpose of producing a turning moment or moments opposite to that effected by a load on the crane tending to tip the frame. The magnitude of such countermoments may be controlled either by the pressure of the cylinder motivating fluid or by the use of a compressible fluid such as air, for example. In the case of incompressible fluids, blocking of the lines of the cylinder by a valve or the like effects shifting of the tipping line of the frame to the rear axle I0 and wheels 12 thereby enabling handling of very heavy loads by the crane but of course with correspondingly greater loads on the rear axle l0 and wheels I2.

From the foregoing, it is now understandable that the provision ofa preloading mechanism such as illustrated and described effectuates a substantial increase in the load carrying capacity of the crane or other lifting device without the necessity of adding further counterweight 36 or shifting thereof on the frame, or of shortening the operating radius of the boom I9, or of relatively shifting the bogie 6 and crane I! on the frame. In addition, it is apparent that this preloading mechanism has utility with various forms of bogies other than that illustrated whether on motor cranes as illustrated or on semi-trailers and the like. 7

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such, be employed.

We therefore particularly point out and distinctly claim as our invention:

1. The combination with a vehicle frame and a plural axle bogie suspended therefrom, of a preloading mechanism interconnecting said frame and bogie and operative to exert upward force on one axle and downward force on another axle, said mechanism comprising a torsion spring bar journalled in said frame, spaced levers non-rotatable on said bar, and links connecting one lever with one axle and another lever with another axle, at least one of said links comprising an extensible hydraulic cylinder assemblage operative when actuated to predeterminately twist said bar.

2. The combination with a vehicle frame and a plural axle bogie suspended therefrom, of a preloading mechanism interconnecting said frame and bogie and operative to exert upward force on one axle and downward force on another axle, said mechanismcomprising a pair of torsion rsprin'g bars on said frame, equalizer bars pivotally connected between their end to said one and another axle respectively, and links connecting said spring bars with the opposite ends of said equalizeribars.

.3. The combination with a vehicle frame and a plural :ax'le bogie suspended therefrom, of a preloading mechanism interconnecting said frame and :bogi'e and .'operative to exert upward force on one axle and downward force on :another axle, said mechanism comprising a pair of torsion spring bars journalled in said frame, spaced levers on each bar lnonerotatable thereon, equalizer bars pivotally connected between their ends to said one and another axle respectively, and links connecting said levers with the opposite ends of said equalizer bars, at least one of said links being extensible whereby to predeterminately twist both of said spring bars.

4. The combination with a vehicle frame and a plural ax le :bogie suspended therefrom, of a preloading mechanism interconnecting said frame and b'o'gie and operative to exert upward force on one axle and downward force on another axle, said mechanism comprising a pair of torsion spring bars journalled in said frame, spaced levers on each 'bar non-rotatable thereon, equalizer bars pivotally connected between their ends to said one and another axle respectively, and links "connecting said levers with the opposite ends of said equalizer bars, at least one of said links comprising an extensible hydraulic 6. The combination with a vehicle frame and i a two axle 'bog'ie including an axle connecting member pivoted between its ends to said frame, of a pair of torsion spring bars on said frame extending longitudinally thereof above said axle connecting member, spaced levers on each bar non-rotatable thereon, equalizer bars pivotally connected between their ends to said axles respectively, and links connecting said levers with the opposite ends of said equalizer bars.

7. The combination with a vehicle frame and a two axle bogie including an axle connecting member pivoted between its ends to said frame, of a pair of torsion spring bars on said frame extending longitudinally thereof above said axle connecting member, spaced levers on each bar non-rotatable thereon, equalizer bars pivotally connected between their ends to said axles respectively, and links connecting said levers with the opposite ends :of said equalizer bars, at least one of said links being extensible whereby to predeterminately' twist both of said spring bars.

8. In combination, a vehicle frame, a support for the front end of said frame, a support for the rear end of said frame comprising a two-axle bogie including front and rear axles and an axle connecting member pivoted between its ends to said frame, and a preloading mechanism interposed between said frame andsaid bogie and comprising a torsion spring bar mounted on said frame and-connected to said axles and twisted to exert downward force on said rear axle and upward force on said front axle thereby imposing a force moment on said frame whereby to increase the load carrying capacity .of said frame insofar as loads disposed rearward of the pivot of said member are concerned.

ROY H. ZEILMAN. MARTIN L. SHEETZ.

REFERENCES CITE?) The following references are of record inthe file of this patent:

UNIT-ED STATES PATENTS Number Name Date 1,412,525 Hewlett Apr. 11, 1922 1,730,273 Hayes Oct. 1, 1929 1,831,631 Manns Nov. 10, 1931 2,091,406 Judd Aug. 31, 1937 2,107,183 Huntman Feb. 1, 1938 2,168,630 Schiff Aug. 8, 1939 FOREIGN PATENTS Number Country Date 432,422 Great Britain July 25, 1935 

